Overlapping exterior siding for houses has been in use for many years. In the early days, such siding was formed of wood. However, wood must be painted at regular intervals for protection and in some instances, paint is ineffective in affording protection as when moisture is able to penetrate through the siding causing blistering and cracking of the paint as well as rotting of the wood.
Various replacement materials for wood in the fabrication of siding have been employed in attempts to retain a pleasing visual effect, while eliminating most of the disadvantages inherent in wood. Typical replacement materials for wood include metal, particularly aluminum, particularly painted aluminum. Other materials have included semi-hardboard, highly-sized insulation board, asbestos sheets, and other materials.
More recently, plastics and particularly vinyl plastics have been used as siding materials. Such plastics may be pigmented to provide desired colors, thereby eliminating the necessity for painting, they are low in cost, have good weather resistance, and do not rot or split. Plastic siding panels have been designed for use alone or with a rigid board-like material called backerboard which is generally formed of materials having insulating properties. Plastic siding panels have been desirably arranged in overlapping and interlocking relationship to provide a pleasing appearance, while concomitantly providing weather resistance and insulation. However, plastic siding heretofore lacked sufficient stiffness so that a wrinkled appearance sometimes resulted. Such plastics are sometimes subject to expansion and contraction upon changes in temperature and readily telegraph very slight irregularities in the materials on which they are placed.
While aluminum and vinyl sidings have become a popular substitute for the periodical or bi-annual painting of homes because of their ready cleanability and resistance to deterioration, these materials have not been entirely satisfactory for the reasons indicated above. Indeed, aluminum siding has become relatively expensive and is inherently less resilient. To overcome the problems in vinyl siding, mentioned above, requires excessive thicknesses, thereby causing such material also to be unduly expensive.
Accordingly, most residential siding made from plastic or aluminum which has reached the market shares the problem of being flimsy, i.e. such siding lacks stiffness in both longitudinal and transverse direction. My U.S. Pat. No. 3,815,310 is one attempt to deal with the problem of lack of stiffness, but one problem with such a construction is that it has plural layers, i.e. it is not unitary, and this also leads to an undesirably high cost of production.
The Lewis U.S. Pat. No. 3,998,021 shows an insulated siding panel assembly comprising an elongated outer panel of deformable sheet material, e.g. PVC, aluminum or steel of about 30 mils, supported to resist deformation by an elongated synthetic resin backing member formed of, for example, closed cellular polystyrene foam, PVC, polyethylene or polyurethane of about 375 mils disposed therebehind. The backing member has at least one longitudinally extending reinforcing rib projecting away from the outer panel and abutting a vertical support surface when the outer panel is mounted thereon. This structure, being a two-piece assembly and having undue thickness, results in a product which is still too expensive.
The patent to Sanders U.S. Pat. No. 4,034,528 relates to an insulating vinyl siding, each panel being composed of a thermoplastic polymer outer facing layer with an ornamental design, a foam filler and a metallic foil backing. The top and bottom edges of each panel form respectively a cooperating and mating tongue and groove arrangement for interengagement with other such siding units. The inert, at least semirigid foam filler, preferably of polyurethane foam, acts as an internal thermal barrier, the metallic foil backing layer being bonded directly to the filler. The facing may be formed of polyolefins, polyvinyls, polycarbonates, etc. Such a three-piece assembly is too thick, its fabrication is difficult, and it results in too expensive a product.
The Hatch et al U.S. Pat. No. 3,504,467 shows an unfoamed PVC siding panel which may, however, be backed by insulating backerboard of glass wool, particle board or plastic foam. This patent describes the advantages and disadvantages of conventional PVC siding, a major disadvantage being lack of stiffness which causes surface distortions. The rigidity of the siding may be increased by ribs located at spaced intervals on its back surface.
Other prior art, located during the course of a preliminary search, is as follows:
U.S. Pat. No. 4,022,643--Clark PA1 U.S. Pat. No. 2,339,489--Kublanow PA1 U.S. Pat. No. 3,936,518--Soda et al PA1 U.S. Pat. No. 3,478,138--Friesner PA1 U.S. Pat. No. 2,816,853--Meyers